FGS-04e

Product Description

The FGS-04e is a low noise 3-axis fluxgate sensor. It extends the frequency range for MT measurements down to DC. The sensor core unit is a Bartington Mag-13 MCL (MC = cylindrical core, L = low noise).

For lower frequencies all transfer functions are linear. This sensor is designed for crustal studies where periods of 10,000 seconds and more are needed. Recording time for those periods are three to eight weeks depending on the data quality (magnetic activity and external interferences by man made noise).

The fluxgate is measuring the total magnetic field (B). A induction coil is measuring dB/dt.

A good coincidence can be seen for periods greater than 30s. For higher frequencies (smaller periods) a fluxgate can not be used for MT. |br|

If the sample rate is too high, the data looks strange:

Coming to lower sampling rates, you start to see the fluxgate data:

The fluxgate has constant transfer function: divide the spectra by 10E-4. Phase shift is zero for f < 1Hz.

Data from Bartington

Performance
Number of axes	Three
Polarity	+ve when pointing North
Full Scale Measuring Ranges	±70µT	±100µT	±250µT
Scaling	143mV/µT	100mV/µT	40mV/µT
Scaling error	±0.5%
Scaling Temperature Coefficient	<±60ppm
Linearity error	0.0015% (least squares fit)
Frequency response at 50µT peak	DC to 1kHz (±5%)
Max Bandwidth at 50µT peak	3400Hz	3100Hz	3000Hz
Max Bandwidth at full scale	3000Hz	2500Hz	1100Hz
Primary Resistance	10Ω ±1.5Ω
Primary Inductance	1000µH typical
Secondary Resistance	36Ω ±4Ω
Secondary Inductance	5600µH typical
Noise:
Standard	≤10pT rms / √Hz @1Hz
Low noise (L)	<6pT rms / √Hz @1Hz (70 and 100µT range only)
Very low noise (Q)	<5pTrms/√Hz at 1Hz (70 and 100μT range only)
Zero Field Offset	≤±30nT
Offset Temperature Coefficient	≤±0.6nT/°C
Perming (Magnetisation Hysteresis)	<2nT (at 1 x Full-scale, when powered)
Orthogonality error between axes	<±0.1° (<±0.2° for MCD and MCDFL)
Alignment to datum face/s	<±0.1° (Mag-13MS only)
Excitation Breakthrough	<5mV pk-pk 15.625kHz typical
Start-up/Settling time	<100ms
Warm-up drift time	15 minutes to meet specifications for scaling
	<60 minutes to meet specifications for noise
	Mag-13® Three-Axis Magnetic Field Sensors

Electrical Specification	Value
Supply Voltage	±12 to 17V
Current Consumption – Positive	35 to 41mA in zero-field
Current Consumption – Negative	13 to 17mA in zero-field
Power Supply Rejection Ratio	120dB
Power-on Surge	+90mA, -25mA, 20ms
Analogue Output	±10V
Output Impedance	10Ω
Test function field in each axis	-1µT ±10%
Maximum cable length @ 12V supply	70μT = 1000m
	100μT = 1000m
	250μT = 800m
	500μT = 650m
	1000μT = 500m
Maximum cable length @ 14V supply	70μT to 500μT = 1500m
	1000μT = 1100m
Cable Length Note	Higher supply voltages will allow longer cable lengths to be used, dependent on cable resistance and magnetometer range.

Environmental
Operating temperature range	-40 to +70°C
Storage temperature range	-40 to +70°C
Compliance (CE, etc.)	EMC BS EN 61326 & RoHS
Additional environmental qualifications	Mag-13MCD 550bar hydrostatic pressure test
Environmental protection / sealing
MC	IP67, metronix uses IP68 enclosure
MS	IP67
MCD	IP68 (5000m)
MCDFL	IP68 (500m)
U	N/A (unpackaged)
U-TPU	N/A (unpackaged)
MSS	IP68 (200m)

Environmental
Operating temperature range	-40 to +70°C
Storage temperature range	-40 to +70°C
Compliance (CE, etc.)	EMC BS EN 61326 & RoHS
Additional environmental qualifications	Mag-13MCD 550bar hydrostatic pressure test
Environmental protection / sealing
MC	IP67
MS	IP67
MCD	IP68 (5000m)
MCDFL	IP68 (500m)
U	N/A (unpackaged)
U-TPU	N/A (unpackaged)
MSS	IP68 (200m)